The document describes the history and development of the Apache web server. Some key points: - Apache was originally developed by the Apache group in 1995 as an open source alternative to NCSA httpd. It was called "A PAtCHy server" as it was initially developed through people contributing patch files to NCSA httpd. - The first official public release was version 0.6.2 in April 1995. Key early features included adaptive pre-fork child processes and a modular/extensible structure and API. - Apache quickly gained popularity and overtook NCSA httpd as the most widely used web server on the Internet after releasing version 1.0 in December 1995.

1. Apache Web Server
• A PAtCHy server: developed by the Apache group
formed 2/95 around a number of people who provided
patch files for NCSA httpd 1.3 by Rob McCool.
• History-http://www.apache.org/ABOUT_APACHE.html
• First official public release (0.6.2) in April 1995
• Add adaptive pre-fork child processes (very important!).
• Modular structure and API for extensibility (Bob Thau)
• Port to multiple platforms. Add documentation.
• Apache 1.0 was released on 12/1/95.
Pass NCSA httpd to be #1 server in Internet.
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2. Web Server Installation Statistics
• http://www.netcraft.co.uk/survey/
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3. Compiling Apache_1.3.12
• Download apache_1.3.12.tar.gz from
http://www.apache.org/dist or closer mirror sites
• $tar xzvf apache_1.3.12.tar.gz
• $ ./configure --prefix=PREFIX
• $ make
• $ make install
• $ PREFIX/bin/apachectl start
• Here PREFIX is the prefix of the directory containing
the distribution, typically it is /usr/local/apache.
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4. CS401 Apache Testbed
• bilbo.uccs.edu and frodo.uccs.edu are installed with
Apache1.3.12.
• /mpc/home/www/sites contains the configuration files
of various web sites contained in the CD-ROM of
Apache text.
• See http://cs.uccs.edu/~cs401/cs401lab.html for
more detail on how to carry out the exercise.
• Copy /mpc/home/www/sites to your directory.
• To avoid conflict, use port # = 8<last 3 digits of SS#>
Add “Port 8<last 3 digits of SS#>“ to httpd.conf.
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5. Apache Exercise Setup
• Replace domain name/IP address on 3rd left Linux PC
www.butterhlies.com 192.168.123.2 with bilbo.uccs.edu 128.198.192.182
sales.butterthlies.com 192.168.123.3 with b2b.uccs.edu 128.198.192.172
www.faraway.com 192.168.124.1 with wait.uccs.edu 128.198.192.202
• Replace domain name/IP address on 4th left Linux PC
www.butterhlies.com 192.168.123.2 with frodo.uccs.edu 128.198.192.183
sales.butterthlies.com 192.168.123.3 with feline.uccs.edu 128.198.192.173
www.faraway.com 192.168.124.1 with walden.uccs.edu 128.198.192.203
• Replace domain name/IP address on 5th left Linux PC
www.butterhlies.com 192.168.123.2 with gandalf.uccs.edu 128.198.192.194
sales.butterthlies.com 192.168.123.3 with gallop.uccs.edu 128.198.192.174
www.faraway.com 192.168.124.1 with wind.uccs.edu 128.198.192.204
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6. Apache Testbed: LAN Setup
• /usr/www/lan_setup script for bilbo:
ifconfig eth0 128.198.192.182
ifconfig eth0:0 128.198.192.172
ifconfig eth0:1 128.198.192.202
• Or on linuxconf for bilbo, select
config | networking | IP aliases for virtual hosts | eth0. Type in
128.198.192.172, 128.198.192.202 for IP aliases
(I have not succeeded in using the above method.)
• Normally we skip lan_setup. We will share the same lan_setup.
Run the above lan_setup if you find the computer is configured
incorrectly (through ifconfig).
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7. Ifconfig command
• Interface configuration command.
• There is an equivalent command ipconfig on win32.
• In Redhat linux, it is in /sbin. I have modified
/etc/profile to include that directory in $PATH.
• Use ifconfig to show the status
• Use ifconfig eth0:1 down to shut down the IP aliase.
• Use ifconfig eth0:1 up to bring it up again.
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8. Apache Web Site Exercises
• Each site.<exercise> directory contains
– conf: configuration files, httpd.conf, srm.conf, access.conf,
mime.types
– htdocs: contains web pages, scripts
– logs: access_log, error_log, httpd.pid, (referer_log, agent_log)
– go: alias of “httpd -d xxSITESxx/site.<name> -X”
-d for the site directory, -X single process execution
• Edit the httpd.conf file. Add the following lines
Port 8<last 3 digits of your SS#>
TransferLog /mpc/home/<login>/sites/site.<name>/logs/access_log
• In go shell script file, replace xxSITESxx with /mpc/home/<login>/sites
replace <name> with the corresponding site name.
• Type go to start the web server
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9. Examine httpd Configuration
• To enhance the security, webuser is created to run httpd
Add “User webuser” and “Group webgroup” to httpd.conf.
• “tail -f <site>/logs/error_log” or “ps aux | grep webuser” to
see if the server is configured and running.
[Sat Feb 7 20:23:57 1998] Server configured -- resuming normal operations or
webuser 13013 0.0 2.2 1260 704 ? S 20:23 0:00 httpd -d /home/cs401
• “tail -f <site>/logs/access_log” to see the processing
results of client requests
usrp16.uccs.edu - - [07/Feb/1998:03:21:16 -0700] "GET / HTTP/1.0" 200 170
• Use a browser (on vinci or other machines) to access
the server a few times with url = http://bilbo:8345/
• “kill `cat <site>/logs/httpd.pid`” to terminate web server.
note that it is back quote ` and not „
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10. Httpd Configuration File
• Apache uses a set of (73) directives to describe to
httpd how the web site should be configured.
http://www.apache.org/docs/mod/directives.html
Each Apache configuration directive is described using a common
format that looks like this:
Syntax: directive-name some args
Default: directive-name default-value
Context: context-list
Override: override
Status: status
Module: module-name
Compatibility: compatibility notes
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11. Block Directives
• Directives that limit the application of other directives.
• Specify by a group like a tag section in html.
• <VirtualHost host[:port]>
...
</VirtualHost>
• <VirtualHost…><Directory dir>, <Files file>,
<Location URL> in ascending order of authority.
<Location> can overwrite others.
• dir, file, URL can specify using wildcards and full
regular expressions preceded by “~”
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12. List of Directives
• User, Group: specify user and group that httpd runs on.
• ServerName: hostname of server (for redirection URL)
• ResourceConfig, AccessConfig: for reading additional
related directives. Can be disabled by /dev/null as value
• Port: specify the port httpd run on
• ServerAdmin:email addr. for browser to do automatic replies.
• DocumentRoot:
• TransferLog, ErrorLog, PidFile: where access,error logs,
httpd.pid should be located. Can be file or pipe “|rotatelogs”
The file is relative to the server root directory
(specified in httpd -d <server root> or /usr/local/etc/httpd)
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13. Directives
• KeepAlive [on|off](on): keep connection alive for n requests before
terminate provided they come in before timeout. n is defined in
MaxKeepAliveRequests <n>(100) directive
• KeepAliveTimeout <n>(15): wait for the next request for n seconds
before terminate the connections.
• Timeout <n>(300): max. time in sec for a block data.
• HostNameLookups [on|off|double](off): do reverse DNS lookup for
logging the domain name of the request.
• MaxClients <n>(256): the limit of # of simultaneous requests
(hence the # of child processes).
• MaxRequestsPerChild <n>(0): Spare(child) server dies after <n>
requests, avoid mem leak. 0 mean infinite requests.
• Min/MaxSpareServers <n>(5/10): # of Idle child servers
• StartServers <n>(5): sets the number of child server processes
created on startup.
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14. Homework#3 Exercise 1:
Site.toddle and Site.simple
• “cp -r /mpc/home/www/sites /mpc/home/<login>“
• Edit the httpd.conf in conf directory
DocumentRoot /usr/www/site.simple/htdocs 
DocumentRoot /mpc/home/<login>/sites/site.simple/htdocs
Port 8<last 3 digits of your SS#>
TransferLog logs/access_log
• Edit go shell script
“httpd -d /mpc/home/<login>/sites/site.<name> [-X]“
go in the site.simple does not have –X.
• go will start the web server. Control-c will terminate it.
• Use browser to visit the site a few times. Remember to specify
the port # in url. For IE browser, type
http://bilbo.uccs.edu:<portno>/ or
http://frodo.uccs.edu:<portno>/ depending which machine
• Check the access_log file. Keep them as record
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15. Homework#3 Exercise 1
User webuser
Group webgroup
ServerName bilbo.uccs.edu or frodo.uccs.edu
DocumentRoot /mpc/home/<login>/sites/site.toddle/htdocs
Port 8<last 3 digits of your SS#>
TransferLog logs/access_log
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16. Site.twocopy
• Create two web servers: one serves customers; one for sales.
There are two directories in site.twocopy.
• In customers/conf/httpd.conf,
replace www.butterthlies.com with bilbo.uccs.edu
add Port 8<last 3 digits of SS#>
• Here BindAddress is used to specify the reception of request
from specific IP address (domain name) by this web server.
BindAddress bilbo.uccs.edu
• In sales/conf/httpd.conf
replace sales.butterthlies.com with b2b.uccs.edu
Replace Listen sales.butterthlies.com:80 with
Listen b2b.uccs.edu:8<last 3 digits of SS#>
• httpd -d /mpc/home/<login>/sites/site.twocopy/customers -X
• httpd -d /mpc/home/<login>/sites/site.twocopy/sales -X
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17. Web Hosting
• Named-based vs. IP-based Virtual Host (VH)
HOST: <name> a unique IP address for each VH
on metaheader different to support a lot of VHs
old browsers not
support this
• Use <VirtualHost hostname[:port]> block directives
• Specify ServerAdmin, DocumentRoot, ServerName,
ErrorLog, TransferLog for individual VH
• Be aware that UNIX File Limits on # of file
descriptors. (default 64)  only support 32 VHs?
• You may want to increase # of child servers.
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18. Site.Virtual/Name-based
• cd /mpc/home/<login>/sites/site.virtual/Name-based
• edit the httpd.conf in conf directory:
• NameVirtualHost 192.168.123.2 
NameVirtualHost 128.198.192.182
Port 8<last 3 digits of SS#>
• <VirtualHost www.butterthlies.com> 
<VirtualHost bilbo.uccs.edu:portno>
Here portno is 8<last 3 digits of your SS#>
• ServerAdmin sales@butterthlies.com 
ServerAdmin <login>@cs.uccs.edu
• /usr/www  /mpc/home/<login>/sites/
• <VirtualHost sales.butterthlies.com> 
<VirtualHost sales-bilbo.uccs.edu:portno>
• Go to start virtual hositng.
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19. Site.Virtual/IP-based
• cd /mpc/home/<login>/sites/site.virtual/IP-based
• edit the httpd.conf in conf directory:
• Add Port 8<last 3 digits of SS#>
right after Group webgroup
• <VirtualHost 192.168.123.2> 
<VirtualHost 128.198.192.182:portno>
Here portno is 8<last 3 digits of your SS#>
• ServerName bilbo.uccs.edu
• ServerAdmin sales@butterthlies.com 
ServerAdmin <login>@cs.uccs.edu
• /usr/www  /mpc/home/<login>/sites/
• <VirtualHost 192.168.123.3> 
<VirtualHost 128.198.192.172:portno>
• ServerName b2b.uccs.edu
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20. Site.Virtual/Mixed-based
• We can mix Name-based with IP-based virtual hosting.
• Change “IP-based” to “Mixed-based”. An error in config file.
NameVirtualHost 128.198.192.182:8888
Port 8888
<VirtualHost bilbo.csnet.uccs.edu:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/customers
<VirtualHost salesbilbo.csnet.uccs.edu:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/salesmen
<VirtualHost 128.198.192.172:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/salesmen
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21. Port-based Virtual Hosting
• Can use one IP address to test many sites.
• Change IP-based to Port-based. An error in config file.
• Different ports map to different sites.
User webuser
Group webgroup
Listen 7888
Listen 8888
<VirtualHost 128.198.192.182:7888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/customers
<VirtualHost 128.198.192.182:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/salesmen
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22. Bonus Exercise #1
• After copying the site.virtual to the nfs mount dir and
executing the httpd, the access_log and error_log
files are empty.
• When use the directory mounted on local disk, there
are no problem.
• See the bonus exercise on
http://owl/~cs401/bonus.html
• Try to explain why this happens.
• A good answer gets 1 point count towards final
grade.
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23. Homework #3 Exercise 2
• Run site.virtual/Name-based, site.virtual/IP-based,
and site.twocopy according to the textbook and verify
the results.
• Keep the access_log and error_log as records.
• Send me email when you finish both exercises.
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24. Homework #3: Problem 3
• Explain why it is possible not to require a new IP
address to host a customer‟s web site, even though it
has a unique domain name.
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